Vol. 5 / Nº 15 - Diciembre 2016

Sebastián Giménez, Gustavo Raichholz, Cristian Froullet, Santiago Dumoulin, Hernán Brouver de Köning, José Luis Sañudo.

Subject revision

Resumen

Las neoplasias de intestino delgado son lesiones poco

frecuentes, representando menos del 5% de los tumo-

res del tracto gastrointestinal (GI). Ante un tumor de

intestino delgado, el diagnóstico diferencial suele ser

amplio, sin embargo algunas de estas lesiones presen-

tan características típicas en tomografía computada

(TC) que sugieren su diagnóstico.

Los tumores del estroma gastrointestinal (GIST), se

presentan en TC como masas de comportamiento

exofítico, redondeadas, con realce heterogéneo. Los

adenocarcinomas de intestino delgado pueden ma-

nifestarse como una lesión estenosante, un pequeño

nódulo o una lesión ulcerativa. Una masa en la raíz del

mesenterio, de bordes espiculados, es la presentación

común de las adenopatías de los tumores carcinoides.

La dilatación aneurismática de un asa, con engrosa-

Abstract

Neoplasms of the small bowel are rare lesions, repre-

senting less than 5% of tumors of the gastrointestinal

(GI) tract. In the presence of a small bowel tumor, the

differential diagnosis is often broad; however some of

these lesions have typical characteristics in computed

tomography (CT) that suggest its diagnosis.

Gastrointestinal stromal tumors (GIST) are presented in

CT as exophytic rounded masses with heterogeneous

enhancement. Small bowel adenocarcinomas may

manifest as a stenotic lesion, a small nodule or an ulce-

rative lesion. A mass of spiculated edges in the mesen-

teric root is the common presentation of lymph nodes

of carcinoid tumors. Lymphomas frequently present

aneurysmal dilatation of a loop with circumferential

wall thickening. Lipomas are displayed as nodular

lesions, with values similar to fat attenuation. The most

Contact information:

Sebastián Giménez.

Diagnóstico por Imagen Junín - Santa Fe capital.

E-mail: sebagimenez66@hotmail.com

Recibido: 10 de agosto de 2016 / Aceptado: 20 de septiembre de 2016

Received: August 10, 2016 / Accepted: September 20, 2016

CT findings of small bowel neoplasms

Revista Argentina de Diagnóstico por Imágenes Revista Argentina de Diagnóstico por Imágenes

Giménez S. et al.

CT findings of

small bowel neoplasms

miento circunferencial de su pared es frecuente de ob-

servar en los linfomas. Los lipomas se visualizan como

una lesión nodular, con valores de atenuación simila-

res a la grasa. Las lesiones malignas más frecuentes de

intestino delgado corresponden a las metástasis, las

cuales pueden invadir la pared intestinal por conti-

güidad, diseminación peritoneal o hematógena. El

objetivo de este trabajo es conocer las principales ca-

racterísticas tomográficas de los tumores de intestino

delgado y realizar una breve revisión de la literatura.

Palabras clave: Neoplasias de intestino delgado, GIST,

carcinoide, linfoma intestinal, adenocarcinoma, lipo-

ma, metástasis.

frequent malignant lesions of the small bowel corres-

pond to metastases, which can invade the bowel wall by

contiguity, hematogenous or peritoneal dissemination.

The aim of this study is to determine the main tomogra-

phic characteristics of tumors of the small bowel and a

brief review of the literature.

Key words: Neoplasms of the small bowel, GIST, car-

cinoid tumor, intestinal lymphoma, adenocarcinoma,

lipoma, metastasis.

IntroductionNeoplasms of the small bowel are rare lesions, re-

presenting less than 5% of tumors of the gastrointes-

tinal tract (GIT). When there are tumors in the small

bowel, differential diagnosis is often broad. However,

many of these tumors display typical characteristics

in CT that help to reach a diagnosis (1).

The role of the radiologist is to determine the lo-

cation and extension of the lesion, the presence of

metastatic lesions and to reach a pre-surgical diagno-

sis. Also, CT helps to detect complications associa-

ted with these tumors, such as digestive hemorrhage,

obstruction and intestinal perforation. This informa-

tion is very useful to plan a pre- and post-surgical

therapy for these patients.

Gastrointestinal stromal tumors (GIST)Currently, they represent the most common non-epi-

thelial tumors of the GIT. They derive from the inters-

titial cells of Cajal, present in the myenteric plexus

of the smooth muscle and are clearly different from

other mesenchymal tumors, such as leiomyoma and

leiomyosarcoma. 95% of these tumors express the

receptor CD117 (KIT). Therefore, the identification of

this tyrosine-protein kinase receptor is key to make a

histopathologic diagnosis of GIST (2).

They are infrequent in patients younger than 40

years old. They appear in elderly patients, except

when associated with predisposing syndromes, such

as Neurofibromatosis type I.

Its location is more frequent in the stomach (42%),

followed by the small bowel (37%), but they can be

present in any portion of the GIT. They can even

appear in the peritoneum, which is the most infre-

quent location (2).

In CT, these tumors appear as masses of soft tissue

density that originate in the gastrointestinal wall and

can protrude towards the lumen or present a predo-

minantly exophytic growth. The size is very variable,

from a few centimeters to voluminous masses that

can measure more than 30 cm. Generally, they are

hypervascular, with a heterogeneous enhancement

after intravenous contrast due to the presence of

central necrosis or hemorrhage (Figure 1). They can

ulcerate towards the lumen of the organ, allowing

the passage of positive endoluminal contrast towards

the necrotic cavity of the tumor. With less frequency,

they appear as cystic masses (3) (Figure 2).

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Most GISTs are benign; however, imaging methods

are not useful to determine if a lesion is benign or

malignant, except in cases where they present distant

metastases. The presence of necrosis is not a reliable

indicator of the aggressiveness of these tumors (4).

The diagnosis of malignancy of these lesions is rea-

ched through histopathologic criteria, such as the

number of mitosis (>10 per high power field), the

size of the lesion (>5 cm), the presence of metastasis,

and the location. Malignant GISTs of the small bowel

are more frequent than gastric tumors (5).

Figure 1. GIST. CT axial image in arterial phase (A) shows a hypervascular lesion (thick white arrow), of exophytic growth with

heterogeneous enhancement due to the presence of necrosis (think black arrow), in contact with a loop of the

proximal jejunum. Axial views (B) with positive oral contrast help identifying the origin of the masses of soft tissue

(thick white arrow) in the bowel wall (think white arrow).

A B

Figure 2. Cystic GIST. CT axial image in arterial phase (A) and coronal image in portal venous phase (B). Cystic, exophytic voluminous

formation (thick white arrow), in contact with a jejunal loop (thin white arrow). There is a parietal nodular lesion

in the jejunal loop showing hyper-enhancement (thin black arrow). Inside the cystic cavity, there is a hydro-air level

that accounts for the communication with the intestinal lumen (arrow head).

A B

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AdenocarcinomaSmall bowel adenocarcinomas are also infrequent

tumors, representing only 0.5% of GIT neoplasms.

However, it is the most frequent malignant tumor of

the duodenum. Almost 50% of these tumors have this

topography, especially close to the ampulla of Vater.

The remaining cases appear in the jejunum and with

less frequency in the ileum (4).

Most cases are sporadic and they predominate in

male patients. The incidence is greater between the

ages of 70 and 90, with a mean age of 65 years old.

Among risk factors there are diseases like celiac di-

sease, Crohn’s disease, history of colorectal cancer,

Peutz-Jeghers Syndrome, and familial adenomatous

polyposis (6).

In cases associated with Crohn’s disease, 70% are

present in the distal ileum.

These tumors can be present in CT as a circumfe-

rential stenotic, irregular lesion and with an abrupt

origin, or as a polypoid or ulcerative lesion. There

are also cases of diffuse parietal infiltration without

narrowing of the organ lumen (Figures 3 and 4).

They can have heterogeneous enhancement after e-v

contrast injection. Besides, they can reduce the intes-

tinal lumen until and produce a lumen obstruction.

In the case of polypoid lesions, they can produce a

mechanic ileum with less frequency by obstruction

secondary to an invagination, acting as the head of

the intussusception.

Carcinoid tumorsThe small bowel is the most frequent location site of

gastrointestinal carcinoid tumors. They derive from

enterochromaffin cells of Kulchitsky, producers of

serotonin of the distal ileum, the most common loca-

tion of this tumor.

The majority of these tumors are sporadic, but

a small number of them is associated with the he-

reditary syndrome of Multiple Endocrine Neoplasia

type 1 (7).

Even though its biological behavior is variable,

they are generally malignant lesions with the capaci-

ty to produce local lymph node and liver metastasis.

They represent the most frequent malignant tumor

of the small bowel.

Its incidence is similar in men and women with a

mean age of 65 years old.

When they produce symptoms, they can be secon-

dary to local effects of the primary tumors (obstruc-

tion, intestinal ischemia or bleeding) or due to hepa-

tic metastases (carcinoid syndrome).

The primary tumor often appears as a small iso-

lated or multiple nodular lesion that rarely measu-

res more than 3.5 cm or as a circumferential parietal

thickening, presenting in both cases a hyper-enhan-

cement with intravenous contrast (Figures 5 and 6).

On the other side, metastatic lesions in mesenteric

lymph nodes or in the liver are often of a greater size

than the primary lesion (1).

The typical aspect of lymph nodes metastasis of the

mesenteric root consists of spiculated masses, often

calcified, accompanied by an extensive desmoplastic

reaction of the mesenteric fat (Figure 5). This reac-

tion is caused by the local production of serotonin

and occasionally, it can be significant in the primary

tumor, extending towards the adjacent mesenterium

and determining a curve of the intestinal wall called

“hairpin turn” (7).

Primary gastrointestinal lymphomaPrimary lymphoma of the GIT is the most common

type of extranodal lymphoma. In most cases, it is

non-Hodgkin type. Its most frequent location is the

stomach, but it can affect any part of the gastrointes-

tinal tract. It represents around 10% of all malignant

tumors of the small bowel, being the third malignant

most common neoplasm of that organ (8).

Two thirds of these tumors are type B cells and are

located in the distal ileum. The remaining one third

is composed by T cells and affects the duodenum

and the jejunum with less frequency (4). It appears

in adults, with a greater incidence in the seventieth

decade of life, and 60% of patients are male (6).

The main risk factors for the development of this

entity are celiac disease, inflammatory bowel disease,

immunodeficiency syndromes and immunosuppres-

sion after solid organ transplantation.

Its preferential location is the distal ileum due to

the existence of multiple lymphoid follicles (Peyer’s

patches) in the submucosa layer.

In CT, it can be seen as an infiltrating pattern that

produces a diffuse thickening of the wall, destruction

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of normal folds and aneurysmatic dilatation of the

lumen due to the replacement of the muscle lumen

that affects the autonomic plexus causing inhibition

of peristalsis (Figure 7). Other types of presentation

include: a unique intraluminal tumoral lesion, a great

exophytic mass that can ulcerate and simulate a GIST

or in the form of multiple small submucosal nodules.

Generally, they are accompanied by mesenteric and

retroperitoneal adenopathies (6).

Most of these neoplasms are soft tumors that do

not cause obstruction of blood vessels nor of the

bowel lumen. The most frequent complication of

these tumors is perforation (4).

Figure 3. Jejunum adenocarcinoma. Entero-graphic CT in portal venous phase, axial (A) and coronal (B) views, with evidence of distal jejunum, and

presence of an infiltrating parietal lesion (arrow), affecting more than half of the organ circumference, without

stenosis of the bowel lumen.

A B

Figure 4. Distal ileum adenocarcinoma. 74-Year-old patient with history of right hemicolectomy

due to colon cancer. CT hydro-enema showing the pre-

sence of circumferential parietal thickening of the distal

ileum (arrow) that does not reduce the bowel lumen.

A

B

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Figure 5. Carcinoid tumor.Axial CT without contrast (A) and with intravenous

contrast in arterial phase in axial (B) and coronal (C)

views showing the formation of soft tissue (thick white

arrow), with some hypervascular calcifications (arrow

head) after contrast injection centered in the mesente-

ric root. It surrounds some arterial vessels (thin black

arrow), which show a subtle reduction of its caliber. It is

accompanied by an extensive desmoplastic reaction of

the adjacent mesenteric fat (thin white arrow). Findings

correspond to a lymphadenopathy of carcinoid tumor.

In the coronal image (C), it can be seen a primary tumor

as a parietal circumferential thickening at the proximal

ileum level (black arrow).

Figure 6. Carcinoid tumor of distal ileum. Axial images in arterial phase CT (A) and portal venous

phase (B) showing a stenotic hypervascular lesion of the

distal ileum (thick arrow), which determines a mechanic

bowel obstruction. Regional adenopathy (thin white

arrow) and distended ileum-jejunum loops with an

important level of liquid into its lumen (arrow head).

There is hypervascular metastasis (C) in the right hepatic

lobule (arrow).

A B

C

A B

C

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LipomasIn most cases, small bowel lipomas are diagnosed in-

cidentally in a CT study, since they are almost always

asymptomatic. They appear with greater frequency

in the duodenum and the ileum. Rarely, they can act

as heads of invagination and cause bowel obstruc-

tion (4) (Figure 8).

The diagnosis is easy with CT. They consist of

homogeneous intraluminal lesions that are well-cir-

cumscribed with attenuation values of -80 to -120

UH. Small bowel liposarcoma is an extremely rare

entity (1).

Small bowel metastasisThey are the malignant lesions that affect the small

bowel with greater frequency. It can be dissemina-

ted through contiguity, hematogenous or peritoneal

spread (4).

Hematogenous metastasis can be originated from

a melanoma or lung, breast or renal cell carcinoma.

They are often presented as multiple nodular lesions

in the anti-mesenteric edge of the small bowel (6).

Contiguity metastasis can be originated from colon

(Figure 9), biliary or pancreatic tumors. The determi-

nation of the primary tumor can be difficult, but it is

useful for the prognosis of the patient.

Peritoneal carcinomatosis can cause tumor deposits

in the serous surface of the small bowel, especially in

its mesenteric edge, and it is seen in mucinous carci-

nomas of the colon, ovary, breast and appendage (1).

ConclusionCT helps to detect small bowel tumors and determine

their extension, location, and specific characteristics

in order to reach a pre-surgical diagnosis. Moreover,

it is very useful for the diagnosis of complications

associated with these neoplasms.

Figure 7. Small bowel lymphoma.Intravenous contrast CT, axial (A y B) and

coronal (C) images. There is an extensive

parietal thickening of the small bowel, with

aneurismic dilatation (thick arrow). Multiple

mesenteric and retroperitoneal lymphadeno-

pathies are seen (thin arrow).

A B

C

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Figure 8. Ileo-ileal invagination due to lipoma. Axial (A) and coronal (B) CT with intravenous contrast, showing an ileo-ileal invagination (thick arrow), due to the

existence of a bowel lipoma acting as a head of intussusception (thin arrow).

A B

Figure 9. Adenocarcinoma of the sigmoid colon extending towards the distal ileum. Sagittal (A) and coronal (B) images in portal venous phase with evidence of a stenotic tumoral formation of the

sigmoid colon (thick white arrow), with invasion of the ileal loop (black arrow).

A B

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